A source clock regenerating section (10) comprises an operating section (2) for taking a weighted average value of a plurality of buffer remaining volumes H that have been sequentially detected, multiplying a predetermined sensitivity coefficient A to this weighted average value, and further adding a predetermined offset value, thereby to obtain a control value U for regenerating the source clock; and an operation control section (5) for setting a local clock (14) to a manipulated variable to be used for calculating the control value capable of converging to the source clock at a high speed during a period from when a source clock regeneration operation has started till when the local clock (14) as a regeneration source clock satisfies a predetermined condition for coming closer to a source clock frequency, and for setting the local clock to the manipulated variable capable of stably regenerating the source clock after this predetermined condition has been satisfied.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A data receiving apparatus comprising: a buffer unit which holds data that has been transmitted from a data transmitting apparatus to a transfer network at a constant speed based on a source clock, and that is then received from the transfer network at a constant speed; and a source clock regenerating unit detects a buffer remaining volume that is a data volume held by said buffer unit, and regenerates the source clock according to this buffer remaining volume, wherein said source clock regenerating unit having, an operating unit which obtains a weighted average value of a plurality of buffer remaining volumes that have been sequentially detected, multiplies a predetermined sensitivity coefficient to this weighted average value, and adds a predetermined offset value, thereby to obtain a control value for regenerating the source clock; and a control unit which sets a regeneration clock to a manipulated variable to be used for calculating the control value capable of converging to the source clock at a high speed during a period from when a source clock regeneration operation has started till when the regeneration clock satisfies a predetermined condition for coming closer to the source clock frequency, and for setting the regeneration clock to the manipulated variable capable of stably regenerating the source clock after this predetermined condition has been satisfied.
2. The data receiving apparatus according to claim 1 , wherein said control unit has a timer for counting a constant time, and the predetermined condition is a lapse of the constant time counted by said timer.
3. The data receiving apparatus according to claim 1 , wherein, said control unit has a time measuring unit for counting a frequency variation range of the regeneration clock, and the predetermined condition is that the frequency variation range of the regeneration clock becomes equal to or lower than a predetermined value.
4. The data receiving apparatus according to claim 1 , wherein, said control unit has a timer for counting a constant time and a time measuring unit for counting a frequency variation range of the regeneration clock, and the predetermined condition is to satisfy one of that the constant time counted by said timer has lapsed and that the frequency variation range of the regeneration clock becomes equal to or lower than a predetermined value.
5. The data receiving apparatus according to claim 1 , wherein, said control unit sets the sensitivity coefficient to a small value and at the same time further adds a predetermined correction value to the offset value, after the predetermined condition has been satisfied.
6. The data receiving apparatus according to claim 1 , wherein, said control unit sets small the weight of the buffer remaining volume at the latest side out of the plurality of buffer remaining volumes used for the calculation of the weighted average value, after the predetermined condition has been satisfied.
7. The data receiving apparatus according to claim 1 , wherein, said control unit changes a predetermined interval for detecting the buffer remaining volume, after the predetermined condition has been satisfied.
8. The data receiving apparatus according to claim 1 , wherein, said control unit further adds a predetermined correction value to the buffer remaining volume of the latest side out of the plurality of buffer remaining volumes used for the calculation of the weighted average value, after the predetermined condition has been satisfied.
9. The data receiving apparatus according to claim 8 , wherein, the correction value is a time threshold value that changes along with a lapse of time toward a final value after the final value has been decided.
10. The data receiving apparatus according to claim 1 , wherein, said control unit sets a multiplication value of the sensitivity coefficient, an average modulus for prescribing the weighted average calculation of the plurality of buffer remaining volumes, and the predetermined interval, to a constant value corresponding to an optimum value.
11. The data receiving apparatus according to claim 8 , wherein, said control unit carries out a plurality of processing in combination from out of the processing of setting the sensitivity coefficient to a small value and at the same time further adding a predetermined correction value to the offset value, the processing of setting small the weight of the buffer remaining volume at the latest side out of the plurality of buffer remaining volumes used for the calculation of the weighted average value, the processing of changing a predetermined interval for detecting the buffer remaining volume, and the processing of further adding a predetermined correction value to the buffer remaining volume of the latest side out of the plurality of buffer remaining volumes used for the calculation of the weighted average value, after the predetermined condition has been satisfied.
12. The data receiving apparatus according to claim 11 , wherein, said control unit adds a predetermined correction value to the buffer remaining volume of the latest side out of the plurality of buffer remaining volumes used for the calculation of the weighted average value, after the predetermined condition has been satisfied, and carries out one or more processing in combination from out of the processing of setting the sensitivity coefficient to a small value and at the same time further adding a predetermined correction value to the offset value, the processing of setting small the weight of the buffer remaining volume at the latest side out of the plurality of buffer remaining volumes used for the calculation of the weighted average value, and the processing of changing a predetermined interval for detecting the buffer remaining volume, after the predetermined condition has been satisfied.
13. The data receiving apparatus according to claim 1 , wherein, when the frequency variation range of the regeneration clock has exceeded a predetermined value, said control unit returns the regeneration clock to an initial set state of before starting the source clock regeneration operation, sets the regeneration clock to a manipulated variable to be used for calculating the control value capable of converging the source clock at a high speed during a period from this initial set state till when the regeneration clock satisfies a predetermined condition for coming closer to the source clock frequency, and sets the regeneration clock to the manipulated variable capable of stably regenerating the source clock after this predetermined condition has been satisfied.
14. The data receiving apparatus according to claim 1 further comprising a setting unit for setting the contents of the setting control that said control unit carries out.
15. A source clock regeneration method for holding data that has been transmitted from a data transmitting apparatus to a transfer network at a constant speed based on a source clock and the data received from the transfer network at a constant speed, for detecting a buffer remaining volume that is a data volume held by the buffer unit, and for regenerating the source clock according to this buffer remaining volume, the source clock regeneration method comprising: a first step of taking a weighted average of a plurality of buffer remaining volumes sequentially detected during a period from when a source clock regeneration operation has been stated till when a regeneration clock has satisfied a predetermined condition for coming closer to the source clock, multiplying a predetermined coefficient to this weighted average value, adding a predetermined offset value thereby to obtain a control value for regenerating the source clock, and outputting the calculated control value and converging the frequency of the regeneration clock to the source clock at a high speed; and a second step of change setting a manipulated variable to be used for the calculation of the control value after satisfying the predetermined condition, and stably controlling the regeneration of the frequency of the regeneration clock.
16. The source clock regeneration method according to claim 15 , wherein the predetermined condition is a lapse of a constant time after the source clock regeneration operation has been started.
17. The source clock regeneration method according to claim 15 , wherein the predetermined condition is that a frequency variation range of the regeneration clock becomes equal to or lower than a predetermined value.
18. The source clock regeneration method according to claim 15 , wherein the predetermined condition is to satisfy one of that a constant time has passed after the source clock regeneration operation has been started and that a frequency variation range of the regeneration clock becomes equal to or lower than a predetermined value.
19. A recording medium recorded with a program for making a computer execute the method described in claim 15 .
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November 1, 2000
January 6, 2004
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